This invention relates to plastic information discs such as digital video discs ("DVDs"), compact discs ("CDs"), compact disc read-only memories ("CD ROMs"), and the like, and more particularly to providing visible image information ("artwork") on such discs. For convenience herein, all such discs will be referred to generically as discs, although it will sometimes also be necessary to specifically mention certain kinds of these discs.
Labels and other ornamentation are needed on discs for such purposes as identifying the information content of the disc, identifying the source (manufacturer and/or distributor) of the disc, making the disc more interesting and appealing to the eye, etc. Such artwork is frequently applied by "silk screening" one of the two major surfaces of the substantially planar disc (the other major surface being the surface through which information recorded on the disc is read by machine from the disc). Silk screening or other generally similar printing techniques can produce extremely attractive results, but these techniques add extra steps to the disc manufacturing process and therefore increase the cost of the discs. It is also known to use so-called "pit art" on discs (see, for example, U.S. patent application Ser. No. 08/579,302, filed Dec. 27, 1995, now U.S. Pat. No. 5,729,533, which is hereby incorporated by reference herein). Such pit art may be produced using technology similar to that used to record or store information on the disc, but instead of the features being generally microscopic (and apparently random to the naked eye) for information recording, more macroscopic features are employed to produce a visible image. Pit art can provide many interesting visual effects, and because it is produced during molding of the disc, it may reduce or eliminate the need for separate printing steps. However, there may be some complexity associated with translating a desired visual image into pit art form.
In view of the foregoing, it is an object of this invention to improve and simplify the provision of visible images on discs.
It is a more particular object of this invention to provide improved and simplified methods for molding visible images into discs.